Vibrational energy relaxation in proteins

An overview of theories related to vibrational energy relaxation (VER) in proteins is presented. VER of a selected mode in cytochrome c is studied using two theoretical approaches. One is the equilibrium simulation approach with quantum correction factors, and the other is the reduced model approach which describes the protein as an ensemble of normal modes interacting through nonlinear coupling elements. Both methods result in estimates of the VER time (sub ps) for a CD stretching mode in the protein at room temperature. The theoretical predictions are in accord with the experimental data of Romesberg's group. A perspective on future directions for the detailed study of time scales and mechanisms for VER in proteins is presented.Comment: 12 pages, 4 figures, accepted for publication in PNA

Structural and dynamical characteristics of mesoscopic H+^+[H2_2O]n_n clusters

Structural and dynamical characteristics pertaining to the solvation of an excess proton in liquid-like nanoclusters of the type [H$_2$O]$_n$ are investigated using Molecular Dynamics experiments. Three different aggregate sizes were analyzed: $n=10,$ 21 and 125. The simulation experiments were performed using a multistate empirical valence bond Hamiltonian model. While in the smallest aggregates the proton occupies a central position, the stable solvation environments for $n=21$ and 125 are located at the cluster boundaries. In all cases, the structure of the closest solvation shell of the excess charge remains practically unchanged and coincides with that observed in bulk water. Compared to results obtained in bulk, the computed rates for proton transfer in clusters are between one and two orders of magnitude slower, and tend to increase for larger cluster sizes.Comment: 16 pages, 6 figures, to be published in Journal of Molecular Liquids, EMLG2006 special issu

Subcellular organization of the renin angiotensin system in the mammalian kidney cortex

Imperial Users onl

Atrial natriuretic factor

The discovery of the first well-defined natriuretic hormone, the Atrial Natriuretic Factor (ANF), has prompted research on its impact on volume regulation in health and disease. The natriuretic, diuretic, and smooth muscle-relaxing properties suggest an important role of this novel hormone in pathophysiological states with sodium or volume retention, such as congestive heart failure or cirrhosis of the liver. Investigations on the implications of ANF in liver disease have been performed for little more than 1 year, and results are still controversial in many respects. At present, it seems very likely that there is no absolute deficiency of plasma ANF in patients with cirrhosis. Moreover, elevated plasma levels in cirrhotics with ascites have been reported by several groups. However, as yet, a molecular characterization of this increased immunoreactivity is still lacking. There is disagreement on the reduced release of and renal response to ANF in subgroups of cirrhotics; however, stimulus-response-coupling might be impaired. Further studies are needed to elucidate the pathophysiological implications and therapeutical potential of ANF in patients with chronic liver disease

Apuntes sobre identidad, soberanía y lengua en la cosmogonía peronista

This article aims to offer an exploration into Peronism within a historical-political framework in order to analyse and deepen the relationship be-tween the construction of national sovereignty and the so-called “cuestión de la lengua”. In turn, diachronically, two main lines of thought will be highlighted: an initial one, characterised essentially by the “discurso his-panista” and another —developed around 1952— in which an Argentine linguistic autonomy is claimed, detached from the Spanish heritage and more inclined, instead, towards a Latin American political-cultural unity. Within this analysis, apart from the indoctrination found in the norma-tive provisions of Peronism and the modelling of consciences through the educational system, this paper aims to return to the “cuestión de la lengua” in order to situate the dichotomous peculiarity of this political movement, and the importance of the policies used to construct the cul-tural framework and the socio-political meanings

From Perugia to Assisi: Cities on the march for peace

El 30 de enero de 1952, en el marco del cuarto aniversario de la muerte de Gandhi, Aldo Capitini, teórico italiano de la noviolencia, convocó a celebrar la «Conferencia Internacional de la noviolencia», en un contexto internacional exacerbado por las entonces fuertes tensiones internacionales. En esta ocasión, Capitini decidió impulsar una iniciativa por la paz, indipendientemente de los partidos políticos y de las religiones; lo hizo mediante un peregrinaje pacífico desde su natal Perugia hasta Asís, cuna de San Francisco, el mensajero de la condena a la utilización de la fuerza y de la violencia contra todo ser viviente u objeto material. El objetivo de Capitini era repensar una ciudad, más bien dos ciudades, a través de una nueva estrategia hechas por «comunidades momentáneas y en movimiento»: la marcha se presentó, entonces, como una oportunidad de demonstrar que «se podía hablar de noviolencia a los violentos». El presente trabajo reconoce que estas premisas corresponden a estrategia diseñada también para persistir en la «revolución abierta», es decir la revolución atravesada por frecuentes procesos de resignificación. Con ello, el ejercicio pretende dar respuesta a dos preguntas fundamentales: ¿Cuáles eran los objetivos de fondo de la marcha concebida por Capitini?, ¿Qué impacto tuvo la estrategia de la marcha en las ciudades de Perugia y Asís y en el panorama político italiano e internacional?On January 30, 1952, in the occurence of the fourth anniversary of Gandhi’s death, Aldo Capitini, the Italian theorist of nonviolence, called for the «International Conference of nonviolence», in an international context exacerbated by the then strong sociopolitical tensions. On this occasion, Capitini decided to promote an initiative for peace, regardless of political parties and religions; he proposed a peaceful pilgrimage from his native Perugia to Assisi, the cradle of St. Francis, the messenger of condemnation of the use of force and violence against every living being or material object. Capitini's goal was to rethink a city, rather two cities, through a new strategy made by «temporary and moving communities»: the march was presented, then, as an opportunity to demonstrate that «one could speak of nonviolence to the violent ones». The present work recognizes that these premises correspond to a strategy also designed to persist in the «open revolution», that is, the revolution crossed by frequent resignification processes. From this perspective, the exercise aims to answer two fundamental questions: what were the basic objectives of the march conceived by Capitini? What impact the strategy of the march had on the cities of Perugia and Assisi and on the Italian and international political scene

APUNTES SOBRE IDENTIDAD, SOBERANÍA Y LENGUA EN LA COSMOGONÍA PERONISTA

This article aims to offer an exploration into Peronism within a historicalpolitical framework in order to analyse and deepen the relationship between the construction of national sovereignty and the so-called “cuestión de la lengua”. In turn, diachronically, two main lines of thought will be highlighted: an initial one, characterised essentially by the “discurso hispanista” and another —developed around 1952— in which an Argentine linguistic autonomy is claimed, detached from the Spanish heritage and more inclined, instead, towards a Latin American political-cultural unity. Within this analysis, apart from the indoctrination found in the normative provisions of Peronism and the modelling of consciences through the educational system, this paper aims to return to the “cuestión de la lengua” in order to situate the dichotomous peculiarity of this political movement, and the importance of the policies used to construct the cultural framework and the socio-political meanings

“Partir es siempre partirse en dos”: una aproximación a las palabras del exilio en la poética de Cristina Peri Rossi

This paper aims to explore the deep inwardness of the exile in the poems and language of the Uruguayan writer Cristina Peri Rossi. In order to understand the key points of Peri Rossi’s poetics, it will be necessary to reconstruct and retrace the historical matrix that generated her departure from the South American country: the harsh repression of civil rights in the early seventies, forced the writer to travel to Barcelona. The linguistic dimension pursued in such works as Descripción de un naufragio, Diáspora (1976), La nave de los locos (1984) and Estado de exilio (2003) builds the pieces of an articulated semantic puzzle that becomes the bearer of one of the most tragic human experiences

Silk Fibroin: a biopolymer platform for innovative pharmaceutical formulation and biomedical devices.

The protein silk fibroin (SF) from the silkworm Bombyx mori is a FDA-approved biomaterial used over centuries as sutures wire. Importantly, several evidences highlighted the potential of silk biomaterials obtained by using so-called regenerated silk fibroin (RSF) in biomedicine, tissue engineering and drug delivery. Indeed, by a water-based protocol, it is possible to obtain protein water-solution, by extraction and purification of fibroin from silk fibres. Notably, RSF can be processed in a variety of biomaterials forms used in biomedical and technological fields, displaying remarkable properties such as biocompatibility, controllable biodegradability, optical transparency, mechanical robustness. Moreover, RSF biomaterials can be doped and/or chemical functionalized with drugs, optically active molecules, growth factors and/or chemicals In this view, activities of my PhD research program were focused to standardize the process of extraction and purification of protein to get the best physical and chemical characteristics. The analysis of the chemo-physical properties of the fibroin involved both the RSF water-solution and the protein processed in film. Chemo-physical properties have been studied through: vibrational (FT-IR and Raman-FT) and optical (absorption and emission UV-VIS) spectroscopy, nuclear magnetic resonance (1H and 13C NMR), thermal analysis and thermo-gravimetric scan (DSC and TGA). In the last year of my PhD, activities were focused to study and define innovative methods of functionalization of the silk fibroin solution and films. Indeed, research program was the application of different methods of manufacturing approaches of the films of fibroin without the use of harsh treatments and organic solvents. New approaches to doping and chemical functionalization of the silk fibroin were studied. Two different methods have been identified: 1) biodoping that consists in the doping of fibroin with optically active molecules through the addition of fluorescent molecules in the standard diet used for the breeding of silkworms; 2) chemical functionalization via silylation

DE PRESIDIOS A HETEROTOPÍAS FRONTERIZAS: ANÁLISIS DE LA TRANSFORMACIÓN HISTÓRICOPOLÍTICA DE CEUTA Y MELILLA

Resumen En la costa norte del litoral marroqui dos pequenos ribetes, Ceuta y Melilla, se ofrecen como anacronicos vestigios del imperio colonial espanol. Los dos enclaves, transfigurados y modelados por los signos que la historia colonial les ha cosido encima, han visto transformada su condicion de simples bases de guerra y apertura al comercio en el Mediterraneo en fronteras europeas encargadas de filtrar el trafico migratorio procedente, principalmente, del Africa subsahariana. ?Como y por que se ha podido, a lo largo de la convulsiva historia de los enclaves, realizar dicha conversion? El presente articulo de investigacion aborda esta pregunta, rastreando y desentranando –a traves de un intenso analisis historico-politico– las circunstancias que han permitido y alentado la transformacion de Ceuta y Melilla en heterotopias fronterizas ubicadas en el linde mas remoto de Europa. Abstract On the northern coast of the Moroccan coast two small cities, Ceuta and Melilla, are offered as anachronistic vestiges of the Spanish colonial empire. The two enclaves, transfigured and shaped by the signs that colonial history has sewn on them, have seen their status transformed from simple bases of war and opening to trade in the Mediterranean, to European borders in charge of filtering the migratory traffic coming mainly from sub-Saharan Africa. How and why, through the convulsive history of the enclaves, has it been possible to carry out this conversion? The present research article addresses this question, tracing and unraveling –through an intense historical-political study– the circumstances that have allowed and encouraged the transformation of Ceuta and Melilla into border heterotopies located at the most remote edge of Europe